In the field of percutaneous surgery and more particularly that of percutaneous bone biopsy, it is known to use various instruments with which it is possible to penetrate the soft tissue parts and then the cortical substance of the bone concerned and to collect samples of organic substances (bone marrow, bone specimens) contained in the bone or in the cavity of the latter.
These instruments are generally known as bone biopsy needles or bone marrow biopsy needles and are generally composed of a trocar or access needle combined with a biopsy cannula. Being more or less sharp, the trocars or access needles allow the practitioner to pass the instrument through the soft tissue parts and then to drill a hole in the bone concerned, in such a way as to reach a zone where a bone biopsy is intended to be performed.
These trocars generally have a hollow outer tube, of which the end is more or less sharp, and within which there slides a rod whose end is tapered in such a way as to perforate the bone, this rod possibly being configured to collect a sample of the tissue which is situated in the cavity.
Such instruments are generally used manually by way of a handle which is rigidly connected, permanently or non-permanently, to the proximal end (end not coming into contact with the bone) of the perforating rod, and which the practitioner turns into order to drill a hole in the bone. In practice, the practitioner brings the end of the outer tube of the trocar into contact with the bone and then rotates the handle in order to cause the end of the rod to penetrate the bone.
Thus, the international application published under the reference WO2006/061514 describes a trocar intended for bone biopsy and comprising an outer tube, of which the distal end is divided into two segments with a helical cutting edge, and in which a sharpened rod slides. This type of instrument is intended to be used manually via a handle.
The manual use of such a trocar, by means of a handle actuated directly by the practitioner, is a classical operating technique that allows the practitioner to finely control the perforation of the bone. However, in some circumstances, particularly when the hardness of the bone requires greater strength to cause the needle to penetrate the wall of the bone, it is sometimes more convenient, both for the patient and for the practitioner, to have available a drive tool, such as a drill, in order to cause the rod to penetrate the bone without application of excessive force.
It is therefore a considerable advantage for the practitioner to have available a trocar whose perforating rod can be actuated equally well by means of a simple handle or by way of a drive tool.
Such a possibility advantageously allows the practitioner to start a surgical procedure manually and then, if the hardness of the bone so requires, to complete the perforation by means of automatic rotational drive, without its being necessary to change the perforating rod and thus risk losing the point of entry into the bone.
However, it requires the availability of an interface device which is able, with one of its ends, to replace the handle used by the practitioner for manual use of the trocar; by fitting to the end of the latter identically to the handle, and by having at its other end an interface element on which the endpiece of a drive tool can be fixed removably.
The device envisioned here thus serves as a coupling element with which the trocar can be driven in rotation by means of a tool.
Among other functions, a device of this kind must be able to ensure relatively precise axial positioning of the drive tool with respect to the trocar, failing which the penetration precision of the trocar could be adversely affected.
In so far as the interface device is intended to ensure the connection of the end of a trocar (sterile and generally disposable item) to equipment of the drill type (naturally reusable and generally non-sterile item), such a possibility also requires that the interface device can be easily associated with means for mounting the drive tool on the end of the trocar and for driving said trocar in rotation while avoiding all contact between the trocar and the drive tool, which contact could cause contamination of one by the other.
The French patent application published under the reference FR 3007636 thus describes an interface system of a simple structure composed of a hexagonal male element, which is mounted on the proximal end of the trocar, and a hexagonal female element, in which the male element engages, the whole thing being joined together in a removable manner by a snap-fit action.
This document also describes how, depending on the rotary drive means in question, the hexagonal female element is either directly integrated in the handle (in the case of manual rotation of the trocar) or integrated in the end of an interface device mounted directly on the output shaft of the rotary drive tool (drill).
In both cases, the hexagonal female element advantageously retains similar morphological features (polygonal portion of the male and female elements) such that the end of the trocar can engage equally well in the handle or in the end of the tool.
Said patent application thus describes a simple and inexpensive interface system by which a trocar can be connected to a means for actuating the latter, which can equally well be a handle or a rotary drive tool. The connection established is a releasable connection permitting a precise axial alignment of the axis of rotation imposed by the actuator and of the axis of the trocar. However, the coupling device described in said application does not, as it stands, permit sterile coupling between the actuator and the trocar.
The U.S. Pat. No. 6,716,215 describes a means offering a solution for connecting a sterile drill bit to a non-sterile drill by way of a sterile bag. The sterile bag, on which a ring is fixed, is intended to receive a drill, allowing the latter to be packaged so that it can be used in a sterile environment.
In the area of connection of the drill to the drill bit, the leaktightness is provided by an O-ring seal, housed in the ring, which seals the body of the drill bit. Leaktightness is obtained by compression of the seal.
However, this solution has the disadvantage that the bag may find itself driven in rotation on account of the seal rubbing on the drill bit, and, by turning, it can the block the rotation of the drill.
The U.S. Pat. No. 7,850,620 describes a system by which a non-sterile drill accommodated in a sterile bag can be connected to a sterile biopsy instrument by means of a coupler which is rigidly connected to the bag. The coupler has a ring which is blocked in translation but free in rotation and on which the bag is welded. This solution does not permit complete leaktightness, since the ring may allow impurities to pass through on account of its functional play. Moreover, taking account of the structure of the coupler, such a device does not exclude the risk of the bag being driven in rotation by the rubbing action and of thus blocking the rotation of the drill.
The patent application published under the reference WO 2015/154188 also describes a system by which a non-sterile drill accommodated in a sterile bag can be connected to a sterile instrument by means of a ring which is integrally connected to the bag and by means of a coupling shaft mounted in the ring. The ring is formed by two concentric hoops screwed onto each other in such a way as to enclose the bag in the area of an opening in the latter, permitting the passage of the coupling shaft through the bag. The leaktightness between the outside and the inside of the bag is provided by an attached seal which is accommodated in the area of the coupling shaft so as to come into contact with the ring when the coupling shaft interacts with the ring.
A major disadvantage of this system lies in the fact that the ring is not designed to be rigidly connected to the drill, with the result that the bag can be driven in rotation by the rubbing action and can thus block the rotation of the drill.
Moreover, the design of the ring and of the coupling shaft is complex, which results in expensive manufacture and assembly of the system parts. Indeed, the ring and the coupling shaft comprise multiple parts which need to be assembled before the instrument is mounted on the drill, in particular by screwing the hoops together and by mounting the ball bearing on the coupling shaft. Moreover, the placement of the seal requires machining to be performed on the coupling shaft and on the ring, which adds to the manufacturing costs.